Pool Care /
What to Put Under an Above Ground Pool
The safest choice is a firm, level, debris-free base with a pool-matched underlayment. On grass, remove sod and roots first, then follow the pool manual.
Archive date: this article was written for PoolSkimmer on Oct 24, 2026 and given the earlier archive date of Apr 25, 2026 so the blog reads as an organized archive. It was not published on that date.
Preparing the ground for an above ground pool
The rule of thumb is to situate the pool on a firm, level base that is free of debris and to use only the underlayment or material your pool manual sanctions. If the pool is to be on grass, one has to start by clearing away the sod, rocks, sticks and roots. This ensures the liner is on smooth ground and the wall gets even support.
The ideal base for a lawn installation
When placing a ground pool on the lawn, the best foundation tends to be the simplest one the manufacturer will approve. In most cases this involves:
- Leveling the area after the grass is cut out
- Compacting the soil so there is no spongy give
- Laying down a pool pad, foam pad or other protective layer if the manual calls for it
Such a base is important for keeping pressure off the pool floor and the liner from wearing out. It also minimizes the risk of the pool settling in an uneven fashion once it is full.
Materials to consider
What is acceptable will vary by brand and model, making the manual the first point of reference. You may find these common options:
- Pads (pool or liner) intended for above-ground models
- Foam board products made for the purpose
- A sand or stone dust base, but only with the manufacturer’s say-so
- Pavers at the feet or support points as per the instructions
One should not be lulled into thinking a material is suitable simply because it is cheap or soft. An unstable or lumpy layer will cause more trouble than it cures.
Things to leave out
There are some clear don’ts when it comes to what goes under the pool. Anything prone to rotting, holding moisture to the liner, or shifting should be avoided. Grass by itself is not a dependable foundation; it will die back and can create soft spots. Other errors include:
- Forgoing preparation and putting the pool straight on the grass
- Having construction debris, roots or rocks beneath the liner
- Using old carpet or loose padding not meant for pools
- Building up the base with multiple layers until it is no longer even
A safe way to prepare the site
It is best to follow a methodical approach:
1. Consult the manual. Adhere to the maker’s setup and base material directions. 2. Walk the site. Check for any slope, puddling, ant hills or compacted patches that could be a problem. 3. Clear the area. Take out all the sod and debris for a clean surface. 4. Firm up the ground. Compact and level before the pool is put in place. 5. Install the underlayment. Set the frame and do a final check for level.
Should the yard have been recently filled in or repaired, give the ground time to settle.
When to get professional help
If the yard has a pronounced slope, or if the soil remains muddy and uneven after a rain, it is time to bring in a site contractor or pool professional. The same applies if you need work done on grading or drainage, or if you have any doubt about whether the base complies with the manual. A substandard base is a recipe for wall distortion and liner stress; it is far wiser to address the site before the pool is filled than to deal with settlement afterwards.
Post-installation care
Once the pool is in, the surrounding area should be kept tidy and monitored for erosion or standing water. Observe the proper protocols with chemical labels and equipment manuals, and wear the right PPE for maintenance. Before opening a skimmer basket, shut the pump off. At the first sign of electrical or structural issues, cease use of the pool and make a call to a pro.
Sources and further reading
- [Hayward: Weekly pool maintenance](https://www.hayward.com/maintenance/weekly-pool-maintenance)
- [Pentair U-3 skimmer manual: suction safety warnings](https://www.pentair.com/content/dam/extranet/nam/pentair-pool/pool-manuals/u-3-skimmers/395010028C.pdf)
- [SwimmingPool.com: Cleaning the skimmer basket](https://www.swimmingpool.com/maintenance/pump&filter/cleaning-the-skimmer&pump-basket)
- [CDC: Use pool chemicals safely](https://www.cdc.gov/healthy-swimming/media/pdfs/Pool-Chemical-Safety-USE-poster-p.pdf)
- [CPSC: Electrical safety in and around pools](https://www.cpsc.gov/safety-education/safety-guides/pools-and-spas/dont-swim-shocks-electrical-safety-and-around-pools)